Date: Sun, 29 Aug 2004 02:11:27 -0400 From: Brian Fundakowski Feldman <green@freebsd.org> To: Anish Mistry <mistry.7@osu.edu> Cc: freebsd-current@freebsd.org Subject: Re: FreeBSD and wine mmap Message-ID: <20040829061127.GG1047@green.homeunix.org> In-Reply-To: <20040829045911.GF1047@green.homeunix.org> References: <200407271731.12282.mistry.7@osu.edu> <200408041828.26762.mistry.7@osu.edu> <20040804223937.GA99521@freebsd3.cimlogic.com.au> <200408101353.22714.mistry.7@osu.edu> <20040829045911.GF1047@green.homeunix.org>
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On Sun, Aug 29, 2004 at 12:59:11AM -0400, Brian Fundakowski Feldman wrote:
> On Tue, Aug 10, 2004 at 01:53:14PM -0400, Anish Mistry wrote:
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> >
> > On Wednesday 04 August 2004 06:39 pm, you wrote:
> > > On Wed, Aug 04, 2004 at 06:28:02PM -0400, Anish Mistry wrote:
> > > > Ok, so we need something like vm_map_findspace(), but for process address
> > > > mapping? ie. pmap_findspace() that will return an address to a large
> > > > enough free chunk?
> > >
> > > That's a good start, just to get something to work with. How this fits in
> > > with the vm code and whether it is ultimately suitable in the long run is
> > > probably up to Alan Cox. For now, just get something that (a) doesn't break
> > > anything else; and (b) lets Wine behave the way it needs to.
> > >
> > > AFAIK, there are still pthread issues with Wine, but those can't be
> > > addressed until the mmap issue has a work-around.
> > I've got a small patch that gets by the initial problem about not being to
> > mmap the memory for the libraries, but the addresses that are mmap'ed seem to
> > seem to overlap with memory that the current pthread implementation want to
> > mmap for the "red zone" when wine tries to create a thread. It can't mmap
> > the "red zone" addresses since all those address mapping where gobbled up
> > before the thread launched.
> > I'll try to figure out a way to maybe leave a space for the "red zone" and see
> > if that works.
> > Someone who actually knows what they are doing should probably take a look.
>
> The red pages are implemented by leaving the memory space unallocated;
> I don't like that one bit -- this will cause those spaces to be allocated
> but given no protection, which should provide the crash feature that the
> guard pages are there for, but be less bogus (and it doesn't use more
> "memory," but it will use a few more vm_map_entrys.
>
> Index: lib/libpthread/thread/thr_stack.c
> ===================================================================
> RCS file: /usr/ncvs/src/lib/libpthread/thread/thr_stack.c,v
> retrieving revision 1.8
> diff -u -r1.8 thr_stack.c
> --- lib/libpthread/thread/thr_stack.c 14 Sep 2003 22:39:44 -0000 1.8
> +++ lib/libpthread/thread/thr_stack.c 29 Aug 2004 04:50:28 -0000
> @@ -214,6 +214,17 @@
> stacksize, PROT_READ | PROT_WRITE, MAP_STACK,
> -1, 0)) == MAP_FAILED)
> attr->stackaddr_attr = NULL;
> + if (attr->stackaddr_attr != NULL) {
> + void *red;
> +
> + red = mmap((char *)attr->stackaddr_attr + stacksize,
> + _thr_guard_default, PROT_NONE,
> + MAP_ANON | MAP_FIXED | MAP_PRIVATE, -1, 0);
> + if (red == MAP_FAILED) {
> + (void)munmap(attr->stackaddr_attr, stacksize);
> + attr->stackaddr_attr = NULL;
> + }
> + }
> }
> if (attr->stackaddr_attr != NULL)
> return (0);
>
BTW, I think you could also use something like this instead of giving
the kernel questionable mmap(2) policy. I haven't compiled/tested
this one due to lack of a breaking WINE application (but the
libpthread change I know seems to work fine.)
--- map_object.c Sun Aug 29 02:02:54 2004
+++ map_object.c.new Sun Aug 29 02:09:22 2004
@@ -152,6 +152,16 @@
mapbase = mmap(base_addr, mapsize, convert_prot(segs[0]->p_flags),
convert_flags(segs[0]->p_flags), fd, base_offset);
+ /*
+ * If the entire area above the ELF data space is already allocated,
+ * go ahead and try the area before the text (and everything else);
+ * skip the first 1024 pages to not allocate any values "near" NULL
+ * thus hiding NULL pointer errors.
+ */
+ if (mapbase == (caddr_t) -1 && base_addr == NULL)
+ mapbase = mmap(getpagesize() << 10, mapsize,
+ convert_prot(segs[0]->p_flags), convert_flags(segs[0]->p_flags),
+ fd, base_offset);
if (mapbase == (caddr_t) -1) {
_rtld_error("%s: mmap of entire address space failed: %s",
path, strerror(errno));
--
Brian Fundakowski Feldman \'[ FreeBSD ]''''''''''\
<> green@FreeBSD.org \ The Power to Serve! \
Opinions expressed are my own. \,,,,,,,,,,,,,,,,,,,,,,\
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